Simultaneous lobing system



June 29, 1954 Filed Oct. 5, 1946 R. s. PHILLIPS 2,682,656

SIMULTANEOUS LOBING SYSTEM 2 Sheets-Sheet l 1 O b I 1 -.-|O 'J [5 TRANSMITTER 4/ '6 k(A+B) (I? 19 k(A-B) I A8 LOCAL MIXER OSClLLATOR MIXER 2o ,21 ZSTAGE |.F. 24 2STAGE LF. PRE-AMPLIFIER PRE-AMPLIFIER COHERENT OSCILLATOR AGC.

LE LF. AMPLIFlER A.G.G. AMPLIFIER vmao 1 K27 'vmao GOMMUTATOR ERROR smum.

ENJENTOR RQLPH S. PHiLLlFS ATTCR N EY June 29, 1954 R. s. PHILLIPS 2,682,656

\ SIMULTANEOUS LOBING SYSTEM Filed Oct. 3, 1946 2 Sheets-Sheet 2 I I I l x i FIG.4

Fl G 2-A (A+B)+G (A-B)+C PULSE PULSE GOMMUTATOR OUTPUT BEFORE RECTIFIGATION x U 1 u -A B 1 A B Y U m F1 A B Z U U INVENTOR Fig. 3 RALPH s. PHJLLIPS ATTORNEY Patented June 29, 1954 UNITED STATES OFFICE m esne assignments, to the United States of America as represented by the Secretary of the Navy Application October 3, 1946, Serial No. 701,039

6 Claims. 1

The present invention relates in general to directional radio systems, and moreparticularly to such systems that yield information that aids in the maintaining of the true'direetion of the antenna, as for example, for keeping the antenna pointed at a desired transmitter or target In radio communication between two directive radio stations or in radar systems, it is often desirable to have an antenna'system which is directional and which further" has means for indicating whether the antenna" is pointed directly at the other station or at the desired target. Such systems as have'been used in the past have involved mechanical lobe switchin'g'or systemmatic antenna scanning; such as conical scanningor other types'of beam scanning. In general, these past systems'arecharacterized by a necessity for moving mechanical parts, 'suc'h'a's rotating antenna configurationsbr rotating capacitor device's and associated-motors, or for maintaining equal amplificationchannels.

Accordingly it' is' a'specificobject of thepresent invention to provide a directive radio system. which will perform the function of a lobe switched or conically scanned antenna or other type of directed antenna'ofthe character 'dis-' cussed without the use-of any 'moving parts. The present system contemplates a radio system which may be either a receiver system or a radar system, as desired, having an-antenna system comprising a pair of'antenna elementswhich may be fed that together these elements produce effectively a single directive beam for transmitting. In receiving, the signalsreceived by the aforementioned individual antenna 'ele'ments are separated and then re'combinedin a'novel fashion to produce a directional error signal.

It is further an object of the'present invention to provide a directive "simultaneous lobe comparison antenna system which will provide a-dir'ectional error signal Without 'moving'parts.

It is another object of the'present invention to provide a directive lobe-comparison antenna which will provide a directionalerr'or signalwithout the need for'maintaining equality in the gains of two or more amplification channels.

These and other objectsof' the-invention may be more fully understood from a-careful-consideration of the following detailed description whentaken with the ac'co'mp'anying drawings in which:

Fig; 1 illustrates 'an'embodim'ent' of theinvention in electrical schematic' formas practiced' in aradar system;

Fig. 2 illustrates the con figuratien "ofwave mitter it is provided, connected-to atransmission line i l. The energy generated by transmitter in is led through transmission line H to a junction of four transmission lines -a,-b-, c, and d, known as a duplexbalancer illustrated-schematically in block [2. For abetter understand= ing of the invention, the duplex-balancer will now be explained in greater detail.

The duplex-balancer is disclosed and sonamed in the co-pending application of Warren .A. Tyrell for Coupling Arrangement for Use in Wave Transmission System, Serial No. 470,810,

filed December 31 1942, now U. S. Patent 2,445,- 895 dated July 27, 1948, and assigned to Bell Telephone Laboratories, Inc. The duplex-balancer is asystem comprising acommon junction of a plurality of transmission 1ines,'as for example, four transmission lines a; b, c, and d with each other or witha fifth line; If the system is matched to eliminatereson-ance in the various lines for the energy being carried therein, theelectrical structure and symmetry of the system may beso arranged that the following characteristics are had among others:

1. Power iedwith line a-passes into lines 0 and d in equal quantities, emerging from c and d in the same phase, no power passing into line b.-

2. Power fed simultaneously into lines 0 and d enters line a in additive fashion and line b in.

subtractive fashion.

The electrical structure should-be such that the lines a, c, and d are joined in parallel and the line b in series to the other, as shown in Fig.- 2 to provide these characteristics. Such a matched arrangement is more specificallytermed a Magic Tee and is described in detail inthe-copending application of Robert H. Dicke for Tran'smission System, Serial No. 581,695, filed March 8, 1945, now U. S. Patent 2,593,120, dated-April15.

1952, wherein certain matching means for a Magic Tee" constructed of wave guides are-disclosed. The above enumerated characteristics 3 are employed in the present invention as Will hereinafter be more fully explained.

Although a duplex balancer may be made of any desired type of transmission line or of circuit elements as discussed and shown in the aforementioned copending application of Tyrell, only that form constructed entirely of wave guides, as for example that illustrated in Fig. 2 will be considered herein, inasmuch as the embodiment of the present invention herein described illustrates the invention as it may be practical using wave guides for transmission lines. Accordingly, in Fig. 2, energy entering line a of Magic Tee I2 will divide and pass into lines and d in equal quantities and in like phase. No energy will enter line b. In order that energy may leave arms 0 and d in like phase it is desirable that these arms be of equal length. Transmission lines [3 and M preferably of equal length are connected between lines 0 and cl and antenna feed elements A and B, thus providing equal phase feeds for these antenna elements. Each of the antenna feed elements A and B provides a lobe pattern, as illustrated in Fig. 2A, and the two elements are so arranged coadjacently that the two lobes are similarly directed and partially overlap in space, so that the antenna may be thought of as a single directive antenna having as axis ZZ located substantially equidistantly between the two lobes.

During transmission an effectively single lobe is transmitted inasmuch as the A and B lobes add in phase to provide in effect a single lobe. Upon reception, however, each lobe will return energy to its own antenna feeds A or B. This energy in turn returns to Magic Tee l2 through arms 0 and d thereof. In accordance with the second characteristic of the Tee as hereinabove set forth, the energy in feeds A and B enters line a of Magic Tee 12 in additive fashion (A+B) and line b in subtractive fashion (A-B). As shown in Fig. 1, the received energy from line it passes through a first receiver protective device [5 and provides a first signal k(A+B) which is proportional in magnitude and has the sense of the algebraic sum of the amplitude of the signals in antenna feeds A and B. Likewise, the received energy leaving arm b passes through a second TR box l6 and provides a second signal 7c(AB) which is proportioned in magnitude to and has the sense of the difference between the amplitude of the signals in antenna feeds A and B. The first signal 70(A-I-B) is fed to a first mixer 1'! while the second signal 7 :(AB) is fed to a second mixer I8. both mixers I l and I8, and is arranged to beat with both signals k(A+B) and lc(AB) simultaneously. Intermediate (I. F.) signals k1(A+B) and k1(AB) are accordingly produced in mixers I! and l 8 respectively. These I. F. signals remain dependent in magnitude and sense upon their parent signals k(A+B) and k(AB). These I. F. signals k1(A+B) and k1(AB) are fed into first and second I. F. preamplifiers 20 and 2 I, respectively, to provide stronger first and second signals 7C2(A+B) and kz(AB) respectively. These preamplifiers 20 and 2| should be matched at least to the extent that the change of phase in the I. F. signals as they pass through the amplifiers should not differ by more than 20 degrees. The signals k2(A+B) and k2(A-B) are fed to and energize windings e of loosely coupled transformers 22 and. 23 respectively. Coherent oscillator 24 (known as a COHO) generates a CW signal C which energizes windings f of transformers 22. and 23. The

A local oscillator I 9 is provided for w cos 0 and :(A-B) cos 0.

frequency of the COI-IO signal must be the same as that of the I. F. signals from amplifiers and 2| to within 4 megacycle, if the pulse lengths of signals A and B are of the order of one microsecond. Transformers 22 and 23 add vectorially the signal 0 to the two I. F. signals k2(A+B) and k2 (A-B) with a resultant I. F. signal in windings g of ks(A-|B) +0 and ks(A-B) +0. These signals are fed to a further stage of amplification represented by amplifiers 25 and 26 respectively. The envelopes of the signals from amplifiers 25 and 26 are of such a nature that they can be analyzed to produce an error signal. Commutator 21 is provided to perform this function. The commutator multiplies the pulse in the (A-B) +C channel by the sign of the pulse in the (A+B) +C channel and rectifies the output to give an error signal of the proper sign. Four examples of the operation of the commutator are shown in Fig. 3. In example (w), the magnitude of A is greater than B, and the sign of the (A+B) +C channel is positive resulting in a positive pulse output before rectification. In example (x) the sign of the (A-l-BH-C pulse is negative but since A B the (A-B) +C pulse is positive, resulting after multiplication, in a negative signal. Examples (y) and (z) are similar possibilities and will be selfexplanatory upon investigation. The outputs of amplifiers 25 and 26 are capacitively coupled to commutator 21 so that the D. C. component of the C signal is dropped resulting in only the pulse itself being transmitted. As previously mentioned, the sign of the error signal is dependent upon the relative size of the A and B signals. The magnitude of the error signal depends on the phase of the A signal relative to the C signal in the I. F., A and B being either in phase or degrees out of phase with each other. Figure 4 shows the vector addition of the three signals A, B, and C. It is apparent that when (A+B) is small compared to C, the commutator inputs are pulses of size and sign of approximately (A+B) With 0 the phase angle between (A+B) and C, then the amplitude of the envelope of the (A+B) +0 channel is |A+B| cos 0+|Cl while that of the (AB) +0 channel is ]A-Bl cos 0+|C| if A is larger than B, and -|AB] cos 0+]C! if B is larger than A. The video pulse is |A+B| cos 0 for the left channel and IA-Bl cos 0 (if A B) or ]AB| cos 0 (if A B) for the right channel. Hence if the pulses of the left and right channels are of the same sign, the A signal is the larger. If the left and right pulses are of different signs, then the B signal is the larger. The commutator thus gives a signal proportional to lA-BI whose sign indicates whether the target is to the right or left.

The automatic gain control feature is added to the system to insure smooth tracking action. Automatic gain control of the COI-IO is necessary to insure that the (A+B) signal when added together is not larger than the COHO' signal C. The automatic gain control of the (AB) I. F. amplifier is designed to remove variations in servo gain due to fading and range.

The error signal output of commutator 21 (a D. C. signal resulting from the rectification of the pulse signals) is fed to a servo mechanism which is so arranged as to maintain automatically the radiation axis ZZ of the antenna array on the target. There is thus provided a convenient and efficient system of automatic tracking, The present system can be further combinedwith 'an MTI system for tracking moving targets nearlarge fixed targets. The antenna has no give away scanning rate and is therefore less susceptible to jamming than present"track-' ing units.

The foregoingfi'e'scription of a system-of automatic lobe "comparison is'not to be construed asa definition of'the invention but is rather to bdconsider'ed illustrative of a preferred "form the invention may take. "For example, coupling transformers "22" and "23 may take a variety of forms, aswell'as the A. G. C. system which may b'eus'ed. The spiritand scope of the invention shall therefore be limited only by 'the appended claims.

What is claimed is:

1. Electric wavecontrolling apparatus comprising, first and second-directive antenna elements arranged to produce respectively first and second adjacent lobes, a first =means operative during the reception of radio signals forproducing'a voltage proportional in amplitude and having the sense of the algebraicsum of the amplitude of the-respective signals-and'a second means simultaneously operative during said reception for producing a second voltage proportional in amplitude and having the sense of the algebraic difference between the amplitude of said respective signals, means for amplifying said first and second signals, a reference oscillator adapted to produce a third signal means for combining vectorially said first and second signals with said third signal to produce fourth and fifth signals, and means for combining and rectifying said fourth and fifth signals to produce a direct current signal having a sense and magnitude essentially proportional to the algebraic difference of said first and second signals.

2. A radio receiver comprising, first and second directive antenna elements having first and second lobes respectively arranged adjacently in a plane to function as a single directive antenna having directivity at least in said plane along an axis lying therein, said elements being adapted during reception to receive first and second sigfirst means operative during reception of said r signals for producing a voltage proportional in amplitude and having the sense of the algebraic sum of the amplitude of the respective signals and a second means simultaneously operative during said reception for producing a second voltt age proportional in amplitude and having the sense of the algebraic difference between the amplitudes of said respective signals, means for amplifying said first and second signals, means to produce a third signal, means for combining said first and second signals with said third signal to produce fourth and fifth signals, first and second means for amplifying said fourth and fifth signals respectively, the output of said first amplifying means being proportioned to the vector sum of said first, second, and third signals and the output of said second amplifying means being proportioned to the vector difference of said first and second signals plus said third signal, and means for simultaneously combining and rectifying the outputs of said amplifying means to produce a direct current signal having a sense and magnitude proportional to the algebraic diiference of said first and second signals, said direct accesses 6. current -si'gi1al becoming zero when energy-is received solely along said radiation axis.

3. A radar systemcomprising a transmitter, first and second antenna-elements arranged to produce respectively first and second adjacent lobes when energized by said transmitter, a Magic Tee so arranged toproduce during reception of radio signals first and second voltages, said first voltage beingproportional in amplitude and havingthesen'se-of the 'algebraic sum of the amplitude "of the respectives'ignals, said second voltage being proportional inamplitude and having the sense of the algebraic difference between the amplitude of saidre'spective signals, first and secondinixers, a single local oscillator to energize sttidfir's'tand secondmixers, the outputs of said first and second mixers being of intermediate frequency but having the same sense and proportinate magnitudeof saidfirst and second voltages, respectively, first and'second means for amplifying said intermediate frequency signals, a coherent oscillatorada'pted to produce a continuous wave signal of frequency similar to said intermediate frequency, first and second means for combining vectorial-ly said continuous wave signal with the'outputs-of saidfirst and second amplifying means respectively, and means for multiplying the outputs of said first and second amplifying means to produce a direct current signal having a sense and magnitude essentially proportional to the algebraic difference of said first and second voltages.

4. A radar system comprising a transmitter, first and second directive antenna elements having first and second lobes respectively arranged adjacently in a plane to function as a single directive antenna having directivity at least in said plane along an axis lying therein, said elements being adapted during reception to receive first and second signals respectively, said signals having equal amplitudes when energy is received solely along said axis and unequal amplitude when said energy is received obliquely to said axis in said plane, a Magic Tee being arranged to produce during reception of said first and second signals third and fourth signals, said third signal being proportional in amplitude and having the sense of the algebraic sum of the amplitudes of said first and second signals, said fourth signal being proportional in amplitude and having the sense of the algebraic difference of the amplitudes of said first and second signals, a local oscillator, first and second mixers in which said third and fourth signals are beat with said local oscillator signal in which are produced fifth and sixth signals respectively, means for amplifying said fifth and sixth signals, a coherent oscillator adapted to produce a seventh signal of a frequency similar to said fifth and sixth signals, means for simultaneously combining said seventh signal with each of said fifth and sixth signals producing eighth and ninth signals, said eighth signal being proportional in amplitude to the vector sum of said fifth and seventh signals, said ninth signal being proportional to the vector sum of said sixth and seventh signals and a commutator adapted to combine said eighth and ninth signals to produce a tenth signal which is proportional in amplitude and has the sense of the difference of said first and second signal.

5. Apparatus for providing voltage to orient the axis of an antenna on a target comprising, first and second lines connected to said antenna for providing two simultaneous overlapping radiation patterns, said overlapping patterns including said axis but diverging equally therefrom, a Magic Tee connected to said lines, means for energizing said lines in similar phase and amplitude through said Magic Tee, first and second receiving channels also connected from said Magic Tee to said feed lines for deriving signals reflected from said target, the signals in said first channel being the algebraic sum of the detected signals in said first and second lines, the signals in said second channel being the algebraic difference of the detected signals in said first and second lines, and means for multiplying the sign and magnitude of said algebraic difierence signals by the sign of said algebraic sum signals to provide an output correction voltage of appropriate sense and magnitude for correcting the orientation of said antenna.

6. In a direction finding system, first and second directive antenna elements having overlapping receiving beam patterns defining an area of constant signal strength which corresponds to the line of direction of the system, said elements being adapted to receive first and second signals respectively, means cooperating therewith to produce simultaneously a first voltage proportional in amplitude and having the sense of the algebraic sum of the amplitude of the receiving signals and a second voltage proportional in amplitude and having the sense of the algebraic difierence of the amplitude of the respective signals, means for equally amplifying said first and second voltages, a reference oscillator for producing a third signal means for vectorially adding to said amplified voltages said third signal for deriving fourth and fifth signals respectively and means for multiplying the magnitude and sense of the fifth signal by the sense of the fourth signal to thereby obtain a correction voltage proportional to the algebraic difference of said first and second signals.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,418,143 Stodola Apr. 1, 1947 2,427,029 Stearns Sept. 9, 1947 2,445,896 Tyrrell July 27, 1948 2,456,666 Agate et a1. Dec. 21, 1948 2,467,361 Blewett Apr. 12, 1949 2,509,207 Busignies May 30, 1950 

